Easiest method is to find a COMPLETE 65/66 V8 based parts car, and strip the complete rear end with brakes, complete steering, including pitman arm, all steering parts, spindles, hubs, etc.
Now, considering getting a parts car that has GOOD parts is virtually impossible, you will be spending a bundle on replacing tie rods, brake parts, etc.
A complete drum to drum rear end, 8", common gears, for a 65/66 (unique width) runs about $100, plus shipping. Figure on new drums, and brake rebuild, and seals. Alternative is to find a Lincoln Versailles rear end, disk brake, and do the same work.
You will either need a new drive shaft, or modify your driveshaft to fit a 6 cyl output with a V8 rear end.
Front end, the relatively cheap method to get disk brakes is to use the 5 bolt granada ( or merc monarch) set up. Can be found, if you have a good day, in the junk yard, for $25, more likely, $150, will need new parts (pads, calipers, rotors, etc) but at least it is Autozone prices.
You then need all new tie rods, sleeves, pitman arm, etc. V8 pitman arm is not repo'd, and goes for around $35 used. Tie rods, sleeves, can be bought at AutoZone or other places.